1. Technical Field
The invention relates to a lighting installation, in particular as a danger light, obstruction light or daytime and nighttime marker, having at least one luminaire, with at least one lighting means being arranged in a housing. The lighting installations in this case are preferably for aviation obstructions, offshore installations or landing strips, for example wind rotors, multi-story buildings, viaducts, towers, drilling platforms or helipads.
2. Prior Art
Such lighting installations are intended to be visible from as far away as possible. At the same time, it is also possible for certain regions to remain blanked out. It is thus the case, for example, that luminaires on aviation obstructions only have to be visible to aircraft, but not for individuals beneath the aircraft obstructions. These individuals would be dazzled by the light emitted. But apart from this, it is intended for the light to be emitted, as far as possible, in all the cardinal-point directions.
The object of the present invention is to provide a lighting installation which emits powerful light on all sides. For this purpose, the lighting installation according to the invention is defined by the following features:
a) the lighting means is in the form of a ring or part of a ring and defines a ring axis,
b) the lighting means is assigned at least a first, wholly or partially encircling reflector surface, which defines an axis of rotation,
c) the ring axis and axis of rotation run essentially parallel to one another or even coaxially with one another.
The abovementioned axes are preferably arranged vertically (perpendicular to the earth""s surface). Correspondingly, the light is emitted mainly at an angle to the abovementioned axes, in particular above a radial plane. As little light as possible should be emitted in the directions below the radial plane.
The lighting installation is preferably designed as a flashing-light installation, with the luminaire in the form of a flashing luminaire and the lighting means in the form of a flashing lighting means. It is also then usually the case that an external or internal electronic circuit is provided for activating the flashing lighting means.
The reflector surface may be of concave form in relation to the lighting means. Particularly advantageous is a parabolic cross sectionxe2x80x94even partly parabolicxe2x80x94when looking at a section parallel to the axis of rotation and tangent thereto. This makes it possible to achieve a particularly good concentration of light.
The lighting means is preferably arranged at a focal point of the at least partially parabolic first reflector surface. Since an annular circumferential lighting means is provided and since the reflector surface also assumes a corresponding circumferential configuration, any number of successive focal points are generated in the circumferential direction, thus forming a circumferential focal line. The focal point can also be defined by a portion of the first reflector surface, such as when the first reflector surface is only partially parabolic.
The first reflector surface and the lighting means are configured and arranged such that light is emitted only into a space preferably above a line running through the lighting means and perpendicular to the axis of rotation. By rotation of the perpendicular line about the axis of rotation, a plane of rotation, preferably a plane of lighting, is set up. The light is meant to enter the space only above the plane of rotation. By arranging the lighting installation at a distance from the earth""s surface, such as on a tower or the like, the light is then only visible to air traffic but not to people on the ground.
Preferably the first reflector surface is arranged essentially below the lighting means, with an outer circumferential border of the first reflector surface lying in a rotation plane known as the border plane, which intersects the lighting means or runs slightly outside of the lighting means. Preferred in this respect is an arrangement of the first reflector surface relative to the lighting means such that the border plane runs along an top side of the lighting means. The xe2x80x9ctop sidexe2x80x9d of the lighting means results from an upright (vertical) arrangement of the axis of rotation. The said circulating border of the first reflector surface represents a transition to non-reflecting regions or a circumferential edge.
The first reflector surface has an inner circumferential border which runs near to a second border plane defined as a rotation plane at an underside of the lighting means. This second border plane can also run along the underside of the lighting means or through the lighting means.
A second reflector surface is also preferably provided which lies opposite the first reflector surface relative to the lighting means. The annular circumferential lighting means defines a (centered) lighting-means plane. The first reflector surface lies essentially on one side of the lighting-means plane and the second reflection plane lies essentially on the other side of the lighting-means plane. Slight overlaps of the lighting-means plane should not be excluded.
The second reflector surface can also have a configuration which is at least partially parabolic as the first reflector surface. This is preferably an embodiment whereby the form is represented at least by parts of the two reflector surfaces as mutually opposite branches. The parabola axis runs preferably through the lighting means and is angled with respect to the center plane of the lighting means in such a way that imaginary and infinite extensions of the two parabola branches run above center plane of illumination.
According to a further idea of the invention, the second reflector surface has an essentially poorer reflecting surface compared to the first reflector surface. Preferably the first reflector surface is metal-coated and the second reflector surface is blackened. The objective is to achieve the best possible reflection on the first reflector surface. The second reflector surface should reflect as little as possible. Inasmuch as a fraction of the light is nevertheless reflected, this fraction should be reflected in a targeted direction.
In an advantageous development the lighting means can be adjusted relative to the first reflector surface and parallel to the ring axis or axis of rotation. This makes it possible to quickly compensate for tolerances in production. In this way it is also possible to set an angle of radiation lying close to a horizontal plane.
The preferred lighting means is an annular xenon flash lamp. Other types of annular lighting means are also applicable. As an alternative, a plurality of LED lamps can be arranged in an annular row, thus forming an annular (or partially annular) lighting means.
In an advantageous embodiment of the invention, a circumferential, cylindrical and transparent covering is provided which is arranged as closely as possible to an outer circumferential border of the first reflector surface. Inasmuch as a second reflector surface is provided, the covering should also be arranged as close to it as possible without any intervening distance. The covering has a circumferential wall which extends parallel to the axis of rotation. A distance of a few mm between the wall and the reflector surface is not detrimental. The narrower the distance between the wall of the covering and the reflector surfaces, the lower the amount of light scatter that is emitted from the luminaire.
The covering advantageously has refracting elements at least in a circumferential section. These may be configured as prismatic and/or catadioptic rings, for example. The objective is to deflect light beams coming directly from the lighting means to a direction as perpendicular as possible to the axis of rotation, or ring axis, or somewhat above the plane perpendicular to it, i.e. above a horizontal direction.
A further idea of the invention provides for a circumferential conical transparent covering with a circumferential main wall, whose diameter increases in the direction of the lighting means, and having a shoulder, connected to the inside of the main wall at the point of its largest diameter, which extends in the direction of the first reflector surface. The shoulder is preferably configured as a continuation of the most outer tangent to the first reflector surface.
According to another idea of the invention, a second reflector surface is provided with diaphragms which prevent the reflected light from being radiated in a direction perpendicular to the axis of rotation. The second reflector surface, either by itself or in conjunction with the screens, has the function of a light trap. This further reduces any light scatter.
Advantageously the light emitted by the lighting means falls on the first reflector surface, is sent directly from the luminaire or strikes other parts of the luminaire""s housing, with said other parts having means for averting a reflection of the light. For example, such means may be screens, control rings or especially poorly-reflecting surface coatings, such as blackened surfaces. The objective here is also to avoid light scatter beyond the luminaire.
A further idea of the invention provides for a support on which the first reflector, a board for accommodating electric components, and a board housing are mounted. The support can be an integral part, centered and running along the axis or rotation or the ring axis, into which the specified components are inserted and secured. Preferably the second reflector surface is also held on the support immediately following the first reflector surface.
The preferred field of application of the lighting installation is a wind-rotor installation. The latter is well-known, comprising a high mast on whose peak a hub with a wind-rotor is mounted. A lighting installation is usually arranged at the very top of the mast. For very high masts the lighting installation takes the form of a flashing light, for shorter masts a blinking light is used. The invention also relates to both of these lighting means.